<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Document</title>
  </head>
  <body>
    <script>
      var foo = '123'
      function print() {
        var foo = '456'
        this.foo = '789'
        console.log(foo) // '456'
      }
      print()
      // window.foo = 789
    </script>
  </body>
</html>
